af_unix: enable handing out pidfds for reaped tasks in SCM_PIDFD

Now everything is ready to pass PIDFD_STALE to pidfd_prepare().
This will allow opening pidfd for reaped tasks.

Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Luca Boccassi <bluca@debian.org>
Cc: David Rheinsberg <david@readahead.eu>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/20250703222314.309967-7-aleksandr.mikhalitsyn@canonical.com
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/net/core/scm.c b/net/core/scm.c
index 358a4e04d46cfc3582e597ca589b06d092c606c2..072d5742440adae36757592c102657a9a93391be 100644 (file)
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -23,6 +23,7 @@
 #include <linux/security.h>
 #include <linux/pid_namespace.h>
 #include <linux/pid.h>
+#include <uapi/linux/pidfd.h>
 #include <linux/pidfs.h>
 #include <linux/nsproxy.h>
 #include <linux/slab.h>
@@ -482,7 +483,7 @@ static void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
        if (!scm->pid)
                return;
 
-       pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
+       pidfd = pidfd_prepare(scm->pid, PIDFD_STALE, &pidfd_file);
 
        if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
                if (pidfd_file) {